(a) Field of the Invention
The present invention relates to a plasma reactor, and more particularly, to plasma reactor for attaining an environmentally friendly process by decomposing and removing various hazardous materials caused by a process chamber in a front part of a vacuum pump.
(b) Description of the Related Art
A process chamber for performing processes such as etching, deposition, cleaning, and so on is installed in a manufacturing line of a semiconductor, a display, a solar cell, and the like, and the process chamber is connected to a vacuum pump to evacuate process gases. Various hazardous materials are discharged from the process chamber, for example, greenhouse gases such as CF4, CHF3, C2F6, C4F8, etc. are discharged in the etching process, an undecomposed precursor is emitted in the deposition process, and greenhouse gases and particle by-products such as NF3, SF6, etc. are discharged in the cleaning process.
Restrictions on emissions of the greenhouse gases that cause global warming have been tightened, and the particle by-products deteriorate the durability of vacuum pump while being accumulated in the vacuum pump. Most of the precursors used in the deposition process are injected inside of the vacuum chamber in a liquid phase or is vaporized by a bubbler, etc., and the discharged precursor which is not used in the deposition process refers to an undecomposed precursor. The undecomposed precursors are cumulated inside of the vacuum pump or between the vacuum pump and a scrubber.
Since there is a high temperature difference inside of the vacuum pump when in the operating and non-operating states, undecomposed precursors of a vapor state and that of a liquid state may coexist. As a result, this may cause an explosion due to being excessively expanded while expansion and shrinking is repeated. In addition, the undecomposed precursor accumulated between the vacuum pump and the scrubber is exposed when replacing the vacuum pump, the scrubber, or pipe, and some of this may cause a fire while violently reacting with air.
A technology for installing a plasma reactor in front of a vacuum pump has been researched and developed in order to decompose or remove various hazardous materials released from a process chamber. However, in a mere pipe-shaped plasma reaction, it has been reported that the decomposition rate of the hazardous materials passing through the center area of a plasma reactor is decreased as the pressure is increased, which may cause a problem that the decomposition rate of the hazardous materials is decreased when the pressure is changed.
Meanwhile, in the decomposition process of the hazardous substances using plasma, oxygen radicals and hydrogen radicals are required to stabilize the greenhouse gases, and for this, a method of inputting water vapor (H2O) to a front part of the plasma reactor is conventionally used.
However, although the method of inputting the water vapor is good in terms of safety of the process, it has drawbacks that the decomposition rate of the greenhouse gases is low and the amounts of oxygen and hydrogen are unable to be individually controlled. In addition, there is a technical difficulty in finely controlling the input of water vapor, and there is a limit that the entire system becomes complex since additional equipment such as a bubbler are required.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.